Method of coating glass thread



Patented Mar. 21,

METHOD OF. COATING GLASS THREAD William M. Camp, Glen Ridge, N. J.,asslgnor to The Clark Thread Company, Newark, N. J., a corporation ofNew Jersey No Drawing. Application March 14, 1940, Serial No. 823,987

1 Claim.

This invention relates to a novel and improved method of forming athread of glass fibers or filaments. As known in the art, usually glassthread is formed of twisted filaments, each filament being extruded ina' continuous length. These filaments, however, can be made into shortlengths, similar to cotton fibers, and spun into yarns, in a similarmanner to that employed in the spinning of rayon stable fiber.

When glass filamentsare formed into thread, the result is a productwhich has certain advantages but which hascertainother very definitedisadvantages. Among the disadvantages is that the thread is quitebrittle, which renders it unsuitable for sewing purposes, particularlyin sewing machines where the thread is subjected to sharp suddenflexing, especially where the machine is operated at high speed. This isthe principal disadvantage which is overcome by the present invention.

For the sake of illustration, I may describe my invention as beingpracticed with a thread made of a large number of ends, for examplefifteen ends, each of which in turnis formed of many fine filaments ofglass fiber, these being twisted together to form a thread. As anexample, glass yarn supplied by the manufacturer, known as 900/2, isplied fifteen times to make a sewing thread. a a

The thread thus formed is then run through a bath of rubber latex orsome equivalent compound of rubber or other adhesive. For the sake ofconvenience, however, the material in the bath will be referred to aslatex. The apparatusfor running the thread through the bath maybe any ofthe usual pieces of apparatus used for such purposes and needs nodescription.

After leaving the bath, the thread is then heated and compressed,preferably -by being passed through'a round hole in a heated die, thediameter of the hole being such that the wet thread in passing throughit is compressed. By that arrangement, the latex is forced into theinterior or the thread, between the fibers or filaments of which thethread is composed, and thus the thread is thoroughly impregnated withlatex and a thin film of latex is formed over the outside surfaces thusprotecting the fibers against abrasion. Preferably, the temperature ofthe die is kept at an ordinary flatiron temperature, say, about 350. Byproceeding in this manne the latex coating is smoothed and burnished or"ironed.

- After the glass yarn has been impregnatedwith latex and run throughthe dies, the mate rial may then be placed in an oven and vul-' canizedin the normal manner. In that case, a suitable vulcanizing agent may beincorporated into the latex prior to impregnation.

I have found that by the method which I have described above, I am ableto producethread which is no longer brittle, but-which may be used as asewing thread. At the same time the coating of latex which is providedon the thread is one which prevents glass filaments or fibers fromcutting or wearing each other while it is being sewed into the cloth.

One of the other advantages of my method is that it makes it possible tomake thread of any desired color. Ordinarily, glass thread has to becolored by coloring the glass from which it is formed, but this methodlimits the number 01' colors that can be obtained. However, with mymethod it is possible to incorporate in the latex any desired dyestuflwhich will give to the finished thread the desired color. There ispractically no limit tothe number of colors which may thus be given tothe finished product.

Since the invention has been found to be particularly useful with sewingthread, I have for convenience used the word thread in referring to theproduct, but by that term I do not intend to limit myself to anyparticular size of thread,

because the invention may be practiced equally well with materials whichare usually referred to as yarn or cord. The word thread" therefore isused to cover any of such equivalent products:

I claim:

The method or treating glass fiber thread which comprises impregnatingsaid thread with latex and then passing the impregnated thread throughthe orifice of a heated die, said orifice having a circular crosssection less than the cross section of the thread and of suchdimensionsthat the thread is compressed during passage through said orifice, andheating the'impregnated thread while it is subjected to said pressure.

WIILIAM M. CAMP.

